Wide Input Dynamic Range Research Articles

An 800MΩ-Input-Impedance 95.3dB-DR Δ-ΔΣ AFE for Dry-Electrode Wearable EEG Recording.

Non-invasive, closed-loop brain modulation offers an accessible and cost-effective means of evaluating and modulating one's mental and physical well-being, such as Parkinson's disease, epilepsy, and sleep disorders. However, wearable EEG systems pose significant challenges for the analog front-end (AFE) circuits in view of µV-level EEG signals of interest, multiple sources of interference, and ill-defined skin contact. This paper presents a direct-digitization AFE tailored for dry-electrode scalp EEG recording, characterized by wide input dynamic range (DR) and high input impedance. The AFE utilizes a second-order 5-bit delta-delta sigma (Δ-ΔΣ) ADC to shape DC electrode offset (DEO) and low-frequency disturbances while retaining high accuracy. A non-inverting pseudo-differential instrumentation amplifier (IA) embedded in the ADC ensures high input impedance (Zin) and common-mode rejection ratio (CMRR). Fabricated in a standard 0.18-μm CMOS process, the AFE delivers 700-mVpp input signal range, 95.3-dB DR, 87-dB SNDR, and 800-MΩ input impedance at 50 Hz while consuming 88.4µW from a 1.2 V supply. The benefits of high DR and high input impedance have been validated by dry-electrode EEG measurement.

On‐chip bias‐generating architecture for an automotive application with a wide input dynamic range

SummaryThis paper presents an on‐chip bias‐generating architecture for automotive applications with a wide input range of 3.8–36 V in a 0.18‐ m high‐voltage bipolar‐CMOS‐DMOS (BCD) process. The proposed architecture effectively manages high‐voltage stress issues with few high‐voltage devices optimizing the silicon area. The proposed bias‐generator comprising crude‐reference and crude‐regulator generates a preliminary low bias voltage for the bandgap‐reference circuit. An adaptive‐biased, with‐capacitor, low‐dropout regulator generates a well‐regulated core supply with low quiescent current and better stability over the wide input range. The adaptive biasing expands the unity gain frequency with increasing load enabling a fast‐transient response. The proposed LDO provides a 5‐V output voltage and a load current of 10 A to 20 mA from 5.5‐ to 36‐V supply with a 500‐mV dropout voltage consuming a very low quiescent current of 5 A. With 0‐ to 20‐mA load step and an output capacitor of 1 F, an undershoot of 40 mV and an overshoot of 55 mV are achieved.

A Low-Power Sensing System of VEGF Concentration With Noise Reduction Using Subsampling Technique for Cancer Diagnosis

This paper presents a monolithic low-power sensing system for early cancer detection. The system uses a CMOS MEMS capacitive transducer with a gold interdigitated electrode (IDE) and DNA aptamers to sense the concentration of vascular endothelial growth factor (VEGF). When the DNA aptamer is immobilized with the VEGF sensor, it generates an electric double-layer capacitance. The low-noise front-end circuits amplify this capacitance change and convert the signal into the frequency domain. To solve the wide input dynamic range and reduce power consumption, a two-step time-to-digital converter (TDC) is utilized. The proposed sub-sampling (SS) technique provides a higher conversion gain to reject noise interference and overcome the increase in noise floor introduced from the decoder due to lower supply voltage. The sub-sampling delay-locked loop (SSDLL), combined with the calibration circuit, enhances TDC linearity and noise performance while preventing calibration noise from degrading conversion accuracy. Finally, the time-based information is converted into digital codes with high power efficiency for early cancer analysis. The system is fabricated in TSMC 0.35 μm MEMS CMOS process with electroplated gold. Measurement results show that the power consumption of the readout circuit and the overall system is only 18 μW and 60.65 μW, respectively. The proposed system improves jitter by 49% and achieves 0.725 mV/pg-mL sensitivity.

Oral Cells-On-Chip: Design, Modeling and Experimental Results.

Recent advances in periodontal studies have attracted the attention of researchers to the relation between oral cells and gum diseases, which is a real threat to overall human health. Among various microfabrication technologies, Complementary Metal Oxide Semiconductors (CMOSs) enable the development of low-cost integrated sensors and circuits for rapid and accurate assessment of living cells that can be employed for the early detection and control of periodontal diseases. This paper presents a CMOS capacitive sensing platform that can be considered as an alternative for the analysis of salivatory cells such as oral neutrophils. This platform consists of two sensing electrodes connected to a read-out capacitive circuitry designed and fabricated on the same chip using Austria Mikro Systeme (AMS) 0.35 µm CMOS process. A graphical user interface (GUI) was also developed to interact with the capacitive read-out system and the computer to monitor the capacitance changes due to the presence of saliva cells on top of the chip. Thanks to the wide input dynamic range (IDR) of more than 400 femto farad (fF) and high resolution of 416 atto farad (aF), the experimental and simulation results demonstrate the functionality and applicability of the proposed sensor for monitoring cells in a small volume of 1 µL saliva samples. As per these results, the hydrophilic adhesion of oral cells on the chip varies the capacitance of interdigitated electrodes (IDEs). These capacitance changes then give an assessment of the oral cells existing in the sample. In this paper, the simulation and experimental results set a new stage for emerging sensing platforms for testing oral samples.

A Ka-Band SATCOM Transceiver in 65-nm CMOS With High-Linearity TX and Dual-Channel Wide-Dynamic-Range RX for Terrestrial Terminal

In this article, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Ka$ </tex-math></inline-formula> -band satellite communication (SATCOM) transceiver is first presented using a standard CMOS technology. The proposed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Ka$ </tex-math></inline-formula> -band SATCOM transceiver consists of a high-linearity transmitter (TX) and dual-channel receiver (RX); both TX and RX are based on direct-conversion architecture. By implementing the dual-channel RX, multiple multiplexing modes, including polarization multiplexing and frequency multiplexing, can be enabled depending on the application. The RX variable gain is distributed in both RF blocks and baseband blocks to achieve a wide input dynamic range. The LNA employs a dual-coupling transformer for a low-noise figure (NF) and wideband input matching; moreover, it enhances the amplifier unilateralization characteristic to mitigate the loading effect from switched attenuators. An adjacent channel interference (ACI) cancellation scheme is proposed to further enhance the RX linearity in the frequency multiplexing mode. In the TX, single-turn high-quality-factor transformer is employed to realize matching network and four-way power combining. A prototype of the SATCOM transceiver is fabricated in a standard 65-nm CMOS process. Under 1.05-V supply voltage, the TX achieves a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{\mathrm {SAT}}$ </tex-math></inline-formula> of 20.5 dBm and an average output power of 12 dBm with 2% error vector magnitude (EVM) and a 37.6-dB ACPR. The dual-channel RX achieves an NF of 5.4 dB, an IIP3 of −30 dBm on the high-gain mode, the ACI cancellation is measured of 7.9 dB with a 100-MHz signal bandwidth.

Wide Input Dynamic Range Fully Integrated Capacitive Sensor for Life Science Applications.

This paper presents a new fully integrated CMOS capacitance sensor chip with a wider input dynamic range (IDR) compared to the state-of-the-art, suitable for a variety of life science applications. With the novel differential capacitance to current conversion topology, it achieves an IDR of about seven times higher compared to the previous charge based capacitive measurement (CBCM) circuits and about three times higher compared to the CBCM with cascode current mirrors. It also features a calibration circuitry consisting of an array of switched capacitors, interdigitated electrodes (IDEs) realized on the topmost metal layer, a current-controlled 300 MHz oscillator, and a counter-serializer to create digital output. The proposed sensor, fabricated in AMS 0.35μm CMOS technology, enables a high-resolution measurement, equal to 416 aF, of physiochemical changes in the IDE with up to 1.27 pF input offset adjustment range (IOAR). With a measurement speed of 15 μs, this sensor is among the fast CMOS capacitive sensors in the literature. In this paper, we demonstrate its functionality and applicability and present the experimental results for monitoring 2 μL evaporating droplets of chemical solvents. By using samples of solvents with different conductivity and relative permittivity, a wide range of capacitance and resistance variations in the sample-IDE interface electric equivalent model can be created. In addition, the evaporating droplet test has inherently fast dynamic changes. Based on the results, our proposed device addresses the challenge of detecting small capacitance changes despite large parasitic elements caused by the ions in the solution or by remnants deposited on the electrode.

Calibration-Free CMOS Capacitive Sensor for Life Science Applications

CMOS capacitive sensors reported for high-accuracy cellular molecular measurements typically suffer from significant parasitic capacitance changes caused by remnants and sediments during the experiment with several biological and chemical reactions. In this article, we propose a novel calibration-free capacitive sensing system that addresses this problem. The proposed CMOS capacitive sensor includes interdigitated electrodes (IDEs), a capacitance-to-current converter with a wide input dynamic range (IDR), a variable reference capacitor, and an oscillator-based analog-to-digital converter (ADC) which has been fabricated using $0.35~\mu \text{m}$ AMS CMOS process. Sweeping the value of the variable reference capacitor from 0.1 fF up to 1.27 pF with a step of 10 fF and repeating the sweep each second during the experiment allows the creation of time-resolved three-dimensional (3-D) fingerprints for the measurement of capacitance variations of the sample-electrode interface resulted from both the target material as well as non-target parasitic capacitances. We have tested the sensor using three different chemical solvents. The four different categories of curves that constitute the fingerprints of the chemicals showed a match with the post-layout simulation results. Capacitance change in the range of 0.416 fF up–1.27 pF can practically be monitored. The electrode area of 110 by $220~\mu \text{m}$ and the micrometer chamber size allows for placing tiny droplets of a few microliters. The generated fingerprint is valid for the chemicals with a conductivity of up to 5 mS/cm.

Fully Differential Touch Screen Controller with Wide Input Dynamic Range for Thin Displays.

As today’s smartphone displays become thinner, the coupling capacitance between the display electrodes and touch screen panel (TSP) electrodes is increasing significantly. The increased capacitance easily introduces time-varying display signals into the TSP, deteriorating the touch performance. In this research, we demonstrate that the maximum peak display noise in the time domain is approximately 30% of the maximum voltage difference of the display grayscale through analysis of the structure and operation of displays. Then, to mitigate display noise, we propose a circuit solution that uses a fully differential charge amplifier with an input dynamic range wider than the maximum peak of the display noise. A test chip was fabricated using a 0.35 μm CMOS process and achieved a signal-to-noise ratio of 41 dB for a 6-mm-diameter metal pillar touch when display pulses with 5-V swing were driven at 100 kHz.

Toward High Throughput Core-CBCM CMOS Capacitive Sensors for Life Science Applications: A Novel Current-Mode for High Dynamic Range Circuitry.

This paper proposes a novel charge-based Complementary Metal Oxide Semiconductor (CMOS) capacitive sensor for life science applications. Charge-based capacitance measurement (CBCM) has significantly attracted the attention of researchers for the design and implementation of high-precision CMOS capacitive biosensors. A conventional core-CBCM capacitive sensor consists of a capacitance-to-voltage converter (CVC), followed by a voltage-to-digital converter. In spite of their high accuracy and low complexity, their input dynamic range (IDR) limits the advantages of core-CBCM capacitive sensors for most biological applications, including cellular monitoring. In this paper, after a brief review of core-CBCM capacitive sensors, we address this challenge by proposing a new current-mode core-CBCM design. In this design, we combine CBCM and current-controlled oscillator (CCO) structures to improve the IDR of the capacitive readout circuit. Using a 0.18 μm CMOS process, we demonstrate and discuss the Cadence simulation results to demonstrate the high performance of the proposed circuitry. Based on these results, the proposed circuit offers an IDR ranging from 873 aF to 70 fF with a resolution of about 10 aF. This CMOS capacitive sensor with such a wide IDR can be employed for monitoring cellular and molecular activities that are suitable for biological research and clinical purposes.

An Adaptive Power Harvester with Active Load Modulation for Highly Efficient Short/Long Range RF WPT Applications

After demonstrating, in previous works, the proof of concept of adaptive rectifiers with active load modulation to operate simultaneously for short/long range RF Wireless Power Transfer (WPT) while maintaining a high Power Conversion Efficiency (PCE), the authors introduced in this paper a power link budget of the proposed adaptive rectifier with a compromise between distance and efficiency. Then, to further exhibit its capabilities and enhance its performance, this paper first introduced a discussion about the parameters preventing the rectifier from operating over a wide range of input powers was performed. Furthermore, active load modulation was implemented and its co-simulation results presented. Finally, an adaptive rectifier was fabricated and its results successfully compared to measured data. It exhibits 40% of PCE over a wide dynamic input range of incident RF power levels from −6 to 25 dBm at the 900 MHz in the Industrial Scientific Medical band (ISM band), with a maximum PCE of 66% for an input power of 15 dBm. The proposed devices are therefore suitable for WPT applications to harvest energy from a controlled source.

Wide‐input dynamic range 1 MHz clock ultra‐low supply flip‐flop

A new wide-input dynamic range flip-flop capable of operation at an ultra-low supply voltage of 0.16 V is presented. The proposed flip-flop named as capacitively boosted sense-amplifier flip-flop (CB-SAFF) utilises a capacitively boosted sense-amplifier master stage to sense the data signals and amplify them to a voltage higher than the supply and below the ground for driving the slave latch stage with improved strength. Using the same size of input/output transistors and load capacitance, the proposed CB-SAFF outperforms existing state-of-the-art sense-amplifier flip-flop designs at a low supply voltage operation from 0.16 to 0.6 V in terms of power delay product and clock to output propagation delay performance metrics. In addition, the proposed CB-SAFF can also sample low-swing data signals down to 0.2 V even at a 0.16 V supply voltage and 1 MHz clock frequency, thus making it highly suitable for applications that demand high speed and low power consumption such as for use in ultra-low voltage Internet of Things, wireless sensor nodes and smart motes.

Dynamic Compression of the Signal in a Charge Sensitive Amplifier: Experimental Results

This paper is concerned with the experimental characterization of a charge sensitive amplifier featuring dynamic signal compression, fast recovery time, low noise, and reduced area occupancy. The device takes the advantage of the nonlinear characteristic of a feedback transistor that behaves like a voltage-controlled capacitance. This property has been exploited to fit a wide input dynamic range into the available output swing. The charge amplifier can be operated in synchronous mode at high frame rates, of the order of few megahertz, thanks to a wide bandwidth, an improved output stage, and a fast reset network. Thanks to the small area occupancy, the amplifier is suitable for integration in a $100\times 100\,\,\mu \text {m}^{2}$ pixel area. All these features make the device a good candidate for applications where a fast front end with a nonlinear response is required, such as in imaging instrumentation for free electron laser experiments. The aim of this paper is to present and discuss the experimental results coming from the characterization of the first prototype of the circuit, which has been designed in a 65-nm CMOS technology. This paper has been carried out in the frame of the PixFEL Project funded by the Istituto Nazionale di Fisica Nucleare, Italy.

An Ultra-Low-Voltage Low-Power Current-Mode True RMS-to-DC Converter

A current-mode CMOS true RMS-to-DC (RMS: root-mean-square) converter with very low voltage and low power is proposed in this paper. The design techniques are based on the implicit computation and translinear principle by using CMOS transistors that operate in the weak inversion region. The circuit can operate for two-quadrant input current with wide input dynamic range (0.4–500[Formula: see text]nA) with an error of less than 1%. Furthermore, its features are very low supply voltage (0.8[Formula: see text]V), very low power consumption ([Formula: see text]0.2[Formula: see text]nW) and low circuit complexity that is suitable for integrated circuits (ICs). The proposed circuit is designed using standard 0.18[Formula: see text][Formula: see text]m CMOS technology and the HSPICE simulation results show the high performance of the circuit and confirm the validity of the proposed design technique.

Long-Reach and High-Splitting-Ratio WDM/TDM-PON Systems Using Burst-Mode Automatic Gain Controlled SOAs

This paper presents novel burst-mode automatic gain controlled semiconductor optical amplifiers (AGC-SOAs) that are utilized as one upstream channel of a repeater in long-reach time- and wavelength-division multiplexed passive optical networks (WDM/TDM-PONs). Two SOAs are cascaded in the AGC-SOAs to achieve high gain. Two-stage gain switching with a fast feed forward (FF) control circuit is applied to the first SOA and the second SOA equalizes output burst frame powers regardless of input powers; the combination plays a key role in expanding the system operating range of long-reach systems. The first SOA with the simple gain control scheme can be also utilized as a preamplifier, which is useful to realize high-splitting-ratio systems without facing any electric supply issues. Unlike conventional burst frame power equalizers which change the gain of a single SOA through an FF control circuit and so do not provide a wide enough input dynamic range for PON applications, our gain control scheme successfully overcomes this issue. It improves the accuracy of output power equalization by reducing the input power range to the second SOA. We develop a prototype that implements this scheme and experimentally confirm that it can expand the system operating range of both long-reach and high-splitting-ratio systems. Although we have only one prototype at this time, experiments and discussions that consider the presence of neighbouring WDM channels support the possibility of WDM operations.

Note: Optical and electronic design of an amplitude-modulated continuous-wave laser scanner for high-accuracy distance measurement.

To utilize a time-of-flight-based laser scanner as a distance measurement sensor, the measurable distance and accuracy are the most important performance parameters to consider. For these purposes, the optical system and electronic signal processing of the laser scanner should be optimally designed in order to reduce a distance error caused by the optical crosstalk and wide dynamic range input. Optical system design for removing optical crosstalk problem is proposed in this work. Intensity control is also considered to solve the problem of a phase-shift variation in the signal processing circuit caused by object reflectivity. The experimental results for optical system and signal processing design are performed using 3D measurements.

Improvement of cochlear implant performance: changes in dynamic range

Abstract Theoretically, a wide input dynamic range (IDR) will capture more of the incoming acoustic signal than a narrow IDR, allowing the cochlear implant (CI) user to hear soft, medium, and loud sound. A narrow IDR may restrict the CI user’s ability to hear soft speech and sound because less of the incoming acoustic signal is being mapped into the CI user′s electrical dynamic range. The overall goal of the study is to provide guidelines for audiologists to efficiently and effectively optimize performance of CI recipients for two difficult listening situations: understanding soft speech and speech in noise. Two variables were studied; the independent variables were IDR and the electric dynamic range of the channels. The dependent variables were six Ling sounds, monosyllabic word test, and speech in noise test. Fourteen patients participated in the study. For each patient, seven programs were created. In each program, dependent variables were assessed in different independent ones. A restricted IDR resulted in poor speech recognition compared with the relatively wide IDR. Subjectively determined T level and most comfortable level (MCL) at the most, not the maximum, comfortable level appears to have a positive effect on both soft sound recognition and speech discrimination. Dynamic range is an important factor -among others- to improve the ability of CI users to understand soft speech as well as speech in noise.

Design of a Photoelectric Detection Circuit in Particle Analysis Apparatus for Clinical Liquid Sample

Based on side lateral scattering technique, a particle analysis apparatus for clinical liquid sample provided a precise and accurate method to acknowledge and transversely compare the particle properties at the micro-level. To improve the detection capability and lessen the lower detection limit of particle size, a photoelectric detection circuit including two parts of pre-amplifier and noise reduction was designed in accordance with the properties of lateral scattering signals. The circuit has the characteristics of working stable at high frequency band, high SNR and wide dynamic input range. Experiments show that the apparatus with the circuit mentioned can detect 0.3μm particle effectively and has broad application prospects in differential blood count, injection quality control and many other areas.

All-optical gain-clamped EDFA using external saturation signal for burst-mode upstream in TWDM-PONs.

While the gain-transient suppression of erbium-doped fiber amplifiers (EDFAs) has been widely studied, the large interval between upstream burst-mode signals from optical network units (ONUs) in time- and wavelength-division multiplexing passive optical networks (TWDM-PONs) presents new challenges. A non-gain-clamped EDFA acting as a preamplifier does not have the desired overshoot on the burst-mode signal when there are only a few ONUs in operation in the TWDM-PON. To solve this problem, we propose an all-optical gain-clamped EDFA (OGC-EDFA) that uses a distributed feedback laser diode to generate a saturation signal. An OGC-EDFA based on a ring laser configuration was also tested to compare the overshoot performance; the both OGC-EDFAs showed negligible overshoot performance. Given the negligible overshoot and wide input dynamic range of the OGC-EDFA, the proposed amplifier is thought to be a simple, low-cost solution for TWDM-PON applications.

Short-pulse controlled optical switch using external cavity based single mode Fabry-Pérot laser diode

We propose and demonstrate a novel scheme for short pulse controlled all-optical switch using external cavity based single mode Fabry- Pérot laser diode (SMFP-LD). The proposed scheme consists of control unit and switching unit as two essential blocks. The basic principle of the proposed scheme is the optical bistability property of SMFP-LD for the control unit and the suppression of the dominant beam of SMFP-LD with injection locking for the switching unit. We also present the analysis of hysteresis width and rising/falling time with change in wavelength detuning which helps to find the optimum wavelength detuning value and power of light beams at different stages of the proposed scheme that gives wide input dynamic power range, high ON/OFF contrast ratio, and low rising/falling time. Input data of 10 Gb/s Non Return to Zero (NRZ) signal is switched at output ports depending upon the control signal generated by the control unit, which comprises of optical SR latch. Output waveforms, clear eye diagrams with extinction ratio of about 11 dB, rising/falling time of about 30 ps and 40 ps, and bit error rate (BER) are measured to validate proposed scheme. No noise floor is observed at output ports up to BER of 10-(12) and the maximum power penalty recorded is about 1.7 dB at a BER of 10-(9) which shows good performance of the proposed short pulse controlled optical switch using SMFP-LDs.

Field Trial of 100-km Reach Symmetric-Rate 10G-EPON System Using Automatic Level Controlled Burst-Mode SOAs

This paper reports the world's first field trial of a 100-km reach symmetric-rate ten gigabit Ethernet passive optical network (10G-EPON) system that uses optical-amplifier-based PON repeaters. Semiconductor optical amplifiers (SOAs) are utilized to handle the 10G-EPON wavelength allocation defined in IEEE802.3av; a fast automatic level control technique is applied to cascaded SOAs for upstream amplification to achieve high gain and wide input dynamic range. An electronic dispersion compensation technique is also applied for downstream detection. These techniques support a 79.5-dB loss budget and 100-km reach transmission with 40 km span lengths. In a field trial, we successfully demonstrate bidirectional real-time uncompressed high-definition television signal transmission over installed standard single-mode fiber links.